Apparatus for preventing deflection of workpiece

ABSTRACT

Apparatus for preventing deflection of a workpiece worked by a grinding machine, for example, comprises a steady rest pivotally mounted on a stationary support, a horizontal supporting shoe and a vertical supporting shoe which are slidably mounted on the steady rest for supporting the workpiece, drive means for feeding the horizontal supporting shoe toward the workpiece while at the same time for pivoting the steady rest to feed the vertical supporting shoe toward the workpiece, and a single contact type measuring device for measuring the dimension of the workpiece. The measuring device is provided with a single measuring feeler adapted to engage the workpiece at a point diametrically opposite the vertical supporting shoe for measuring the dimension of the workpiece.

United States Patent [191 Asano et a1.

[ APPARATUS FOR PREVENTING DEFLECTION OF WORKPIECE [75] Inventors: l-liroaki Asano, Chiryu; lkuo Otsu,

Aichi-ken, both of Japan [73] Assignee: Toyoda Koki Kabushiki Kaisha,

Kariya-shi, Aichi-Ken, Japan [22] Filed: Nov. 15, 1971 [21] Appl. No.: 198,890

[30] Foreign Application Priority Data ll/l955 Alvord....- 51/238 S X l/l964 Price ct al. 51/238 S X Primary Examiner-Jiarold D. Whitehead Assistant Examiner-Nicholas P. Godici Att0rney E. F. Wenderoth, John E. Lind et a1.

[57 ABSTRACT Apparatus for preventing deflection of a workpiece worked by a grinding machine, for example, comprises a steady rest pivotally mounted on a stationary support, a horizontal supporting shoe and a vertical supporting shoe which are slidably mounted on the steady rest for supporting the workpiece, drive means for feeding the horizontal supporting shoe toward the workpiece while at the same time for pivoting the steady rest to feed the vertical supporting shoe toward the workpiece, and a single contact type measuring device for measuring the dimension of the workpiece. The measuring device is provided with a single measuring feeler adapted to engage the workpiece at a point diametrically opposite the vertical supporting shoe for measuring the dimension of the workpiece.

' 3 Claims, 5 Drawing Figures PAIENIElIm am 3.743.490

SHEEI 1 If 3 IN VENTORS fls d w $124 ATTORNEYS PATENIEDJUL' a ma 3. 743 '490 sum 2 0f 3 INVENTORS hawk A 1 m BYZOJM-LHM #fiM ATTORNEYS am 3 0f 3 I N VENTORS ATTORNE S PMENIED JUL 3 I975 APPARATUS FOR PREVENTING DEFLECTION OF WORKPIECE BACKGROUND OF THE INVENTION This invention relates to an apparatus for preventing the deflection of a workpiece while it is being worked by a grinding machine and move particularly to a steady rest having a horizontal supporting shoe and a vertical supporting shoe cooperating with a measuring device mounted on the steady rest for finishing the workpiece to a definite diameter.

When grinding a workpiece which has a tendency to flex and including a number of stepped sections to be successively finished to different dimensions by means of a digitally controlled grinding machine without dismounting the workpiece, it has been the practice to support the portion of the workpiece having the largest tendency of flexure or deflection by means of supporting shoes of a steady rest and the operation of the grinding machine is controlled by a measuring device having a feeler or probe contacting the portion of the workpiece being worked independently of the steady rest.

However, where the axial length of the section of the workpiece to be worked is extremely short, application of the supporting shoes and the measuring feeler of the measuring device to the same section of the short axial length causes interference between the supporting shoes and the measuring feeler.

To obviate this difficulty, in prior art devices, the mounting position of the steady rest is changed during the grinding operation to a position wherein the supporting shoes of the steady rest do not interfere with the operation of the measuring apparatus or the supporting shoes of the steady rest are disengaged from the workpiece during the measuring operation concurrently with the reduction of the speed of the grinding wheel to a value which will not deflect the workpiece.

However, the former measure requires the changing of the mounting position of the steady rest during the grinding operation. To this end, it is necessary to use special means for changing the mounting position which complicates the operation and construction. Moreover, as the supporting shoes are often engaged at positions different from the position at which the maximum deflection of the workpiece occurs, it becomes impossible to effectively prevent flexure of the workpiece. A latter measure results in the decrease in the efficiency of the grinding operation.

SUMMARY OF THE INVENTION It is an object of this invention to provide an improved apparatus for preventing deflection of a workpiece during the grinding operation thereof. A further object of this invention is to provide a new and improved apparatus for preventing deflection of a workpiece, which comprises a steady rest for supporting the workpiece and a measuring device mounted on the steady rest whereby to reduce the transverse width of the assembly so as to enable grinding to a definite diameter of a workpiece of short axial length.

Another object of this invention is to provide a novel combination of a steady rest and a measuring device of the single contact type which can provide measuring accuracies equal to those of a two point contact type measuring device by utilizing one supporting shoe of the steady rest as the measuring feeler.

Still another object of this invention is to provide an improved combination of a steady rest and a measuring device in which the supporting shoes of the steady rest are automatically advanced toward the workpiece to follow the reduction in the diameter of the workpiece so as to effectively prevent flexure thereof and wherein the definite dimension measuring device is moved to the inoperative position so as not to interfere with the mounting and dismounting of the workpiece.

In accordance with this invention there is provided an apparatus for preventing the deflection of a workpiece comprising a steady rest pivotally mounted on a stationary support, a horizontal supporting shoe and a vertical supporting shoe'which are used to support a workpiece, the supporting shoes being slidably mounted on the steady rest, drive means for feeding the horizontal supporting shoe toward the workpiece while at the same time for pivoting the steady rest to feed the vertical supporting shoe toward the workpiece, and a single contact type measuring device mounted on the steady rest for controlling the operation of the grinding machine, in accordance with the measured dimension of the workpiece, the measuring device having a single measuring feeler adapted to engage the workpiece at a point diametically opposite the vertical supporting shoe for measuring the dimension of the workpiece.

The measuring device is moved to and from the working position in which its feeler or probe is brought into contact with the workpiece so that in the retracted position it does not interfere with the mounting and dismounting operations of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a side elevation of one embodiment of this invention;

FIG. 2 is a left hand side view of the apparatus shown in FIG. 1;

FIG. 3 is a top plan view of the apparatus shown in FIG. 1;

FIG. 4 is a cross-sectional view taken along a line IV-IV in FIG. 2, and

FIG. 5 is a cross-sectional view taken along a line V-V in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of this invention shown in the accompanying drawing comprises a slide table I mounted on the bed (not shown) of a grinding machine. Table 1 supports a swivel table 2 to which is secured a pedestal 3 by means of clamping nuts 4. A steady rest 5 is pivotally mounted on a projection of pedestal 3 by means of a pivot pin 6. A lower vertical supporting shoe 7 and 'a horizontal supporting shoe 13 are reeiprocatably mounted on the steady rest 5. Thus, the lower supporting shoe 7 is slidably received in a bore formed in the fore end of the steady rest 5 and is manually adjusted in the vertical direction by means of screw threads 9 and a knob 10 to assume a position corresponding to the outer diameter of a workpiece W. As shown in FIG. 4, rotation of the lower supporting shoe 7 is prevented by a pin 12 engaging an elongated groove 11 axially formed on the periphery of the shoe 7 .At the outer end of the lower supporting shoe 7 is secured a tip 8 adapted to engage the periphery of the workpiece W.

The horizontal supporting shoe 13 is received in a bore horizontally formed in the steady rest 5 to be slidable in the horizontal direction and is driven by feed screw threads 16 formed on the inner end of a feed shaft 15. The horizontal supporting shoe is reciprocated by means of a knob 17 secured to the outer end of feed shaft via key 210. Again the rotation of the horizontal supporting shoe 13 is prevented by a pin 24 engaging an elongated groove 23 axially formed on the periphery of shoe 13. A tip 14 is mounted on the outer end of the shoe 13. The horizontal supporting shoe 13 is adjusted manually by knob 17 and is fed automatically by the operation of a feed piston-cylinder assembly 25.

More specifically, a sleeve shaft 18 having a pinion 22 thereon is loosely mounted on the feed shaft 15, and a clutch member 19a is keyed to the outer end of shaft 18. The other clutch member 19b cooperating with clutch member 190 is secured to feed shaft 15 to be slidable in the axial direction by means of a key 21 on the inner side of knob 17. A spring is interposed between clutch members 19a and 19b to urge them to disengage. With this construction, when the set screw 17a threaded into feed shaft 15 is loosened the knob 17 and clutch member 19b are urged to the left by the force of spring 20 to disengage the clutch members so that rotation of knob 17 does not result in the rotation of sleeve shaft 18 but causes feed shaft 15 to rotate thus reciprocating the horizontal supporting shoe 13 by feed screw 16.

The automatic feed mechanism for the horizontal supporting shoe 13 comprises a rack 26 formed on the piston rod housed in the feed piston-cylinder assembly 25 and meshing with the pinion 22 on the sleeve shaft 18. Upon actuation of the piston-cylinder assembly 25, the rack 26 is moved in the vertical direction to rotate feed shaft 15 via pinion 22, clutch members 19a and 19b and key 21 to advance the horizontal supporting shoe 13 as the diameter of the workpiece W is reduced. The operation of the piston-cylinder assembly 25 is also utilized to automatically move upwardly the lower supporting shoe 7 as the diameter of the workpiece W is reduced. More particularly, another shaft 27 formed with a pinion 28 meshing with rack 26 is rotatably received in a horizontal bore formed in the steady rest 5. A bevel gear 29a is secured to the inner end of shaft 27 to mesh with a bevel gear 29b secured to the upper end of a vertical feed shaft 30 for the lower supporting shoe 7, the feed shaft 30 being supported on the lower portion of the steady rest. Feed screw threads 31 i are formed on the lower end of the vertical feed shaft 30 to engage a contact piece 32. The lower end of contact piece 32'is in the form of a sphere 34 seated on a seat 35 mounted on the horizontal leg of the pedestal 3. A

pin 33 is provided to prevent the rotation of the contact piece 32. With this construction, as the piston-cylinder assembly 25 is actuated, rack 26 rotates shaft 27 through pinion 28 to lower the contact piece 32 through bevel gears 29a and 29b, and feed screw threads 31. Thus, the steady rest 5 is bodily rotated a little in the counterclockwise direction about pivot pin 6 whereby the lower supporting shoe 7 is moved upwardly to follow the reduction in the outer diameter of the. workpiece W.

A single point contact type measuring device is mounted on the top of the steady rest 5 to be movable toward and away from the workpiece W as diagrammatically shown in FIG. 1.

More particularly, an operating cylinder 36 for the measuring device 40 is mounted on the upper surface of the steady rest 5. A bracket 37 for supporting the measuring device is secured to the outer end of the piston rod operated by cylinder 36. The axial movement of bracket 37 is guided by a horizontal pilot bar 38 connected to the steady rest 5 by means ofa bearing 39. The single point contact type measuring device 40 is mounted on the bracket 37 to be adjustable in the vertical direction.

The measuring device 40 may be of any conventional design. For example, as shown in FIG. 5, it comprises a single feeler or probe 41 which is yieldingly mounted on the measuring head 42 by means of a criss-cross spring 43, and a differential transformer 45 having a core operably connected to the feeler 41. A bolt 44 is provided to limit the movement of feeler 41. During the grinding operation of the workpiece W the measuring device 40 is advanced toward the workpiece by the operation of cylinder 36 to bring the feeler 41 into engagement with the peripheral surface of the workpiece. Upon completion of the grinding operation, the measuring device 40 is retracted by the operation of the cylinder 36 to a position which does not interfere with the mounting and removal of the workpiece. The apparatus described above operates as follows. First, the pedistal 3 is moved to a position at which the flexure of the workpiece is the maximum. Then the lower supporting shoe 7 is manually adjusted to contact the peripheral surface of the workpiece by rotating knob 10. Further, the horizontal supporting shoe 13 is manually adjusted by turning knob 17 while clutch members 19a and 19b are maintained disengaged. Thereafter, clutch members 19a and 19b are permitted to engage each other. The grinding operation is then started. The measuring device 40 is advanced by the operation of cylinder 36 to cause its feeler 41 to engage the upper surface of the workpiece at a point diametrically opposite the lower supporting shoe 7. At the same time pistoncylinder assembly 25 is operated to feed horizontal supporting shoe 13 in the forward direction, thereby to follow the decrease in the outer diameter of the workpiece W. Further, the steady rest 5 is rotated upwardly or in the counterclockwise direction about pivot pin 6 by the rotation of feed shaft 30 for the lower supporting shoe. This also raises the lower supporting shoe 7 to follow the reduction in the diameter of the workpiece thus 7 maintaining a predetermined contact pressure between the lower supporting shoe and the workpiece- In this manner, during the grinding operation, the workpiece is always maintained steadily or prevented from flexing by the horizontal supporting shoe l3 and the lower supporting shoe 7 while at the same time the dimension of the workpiece is measured by the measuring device 40. The measuring device 40 is of the single point contact type utilizing only one measuring feeler 41. Actually, however, since the measuring device 40 and the lower supporting shoe 7 are mounted on the steady rest 5 which is rotated to follow the reduction in the outer diameter of the workpiece feeler 41 and lower supporting shoe 7 are rotated in unison by the steady rest by an amount corresponding to the decrease in the outer diameter of the workpiece. In other words, actually the measuring device 40 acts as a two point contact type measuring device.

According to this invention, since the measuring device is mounted on the steady rest the transverse width of the assembly can be reduced so that it is possible to grind a workpiece of an extremely short axial length to a definite dimension by supporting it with the supporting shoes. In addition, since the lower supporting shoe is used to act also as one of the measuring feelers, the measuring device can provide the high measuring accuracies of a two point contact type measuring device notwithstanding the fact that actually the measuring device is of the single contact type. The pair of supporting shoes of the steady rest are automatically moved by a single driving device to follow the reduction of the diameter of the workpiece during the grinding operation thereof so that it is possible to positively prevent any flexure of the workpiece. Since the measuring device is mounted to be movable with respect to the pair of supporting shoes it is possible to readily mount and dismount the workpiece without interference from the measuring device thus increasing the working efficiency.

While the invention has been shown and discribed in terms of a preferred embodiment thereof it should be understood that the invention is by no means limited to the specific embodiment illustrated but that many changes and modifications may be made without departing from the true spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. Apparatus for a machine tool for preventing the deflection of a workpiece which is rotatably mounted at the opposite ends thereof by a pair of spaced aligned workpiece supporting devices, comprising:

a stationary support having a projection thereon;

a steady rest pivotally mounted on said projection at one end thereof;

a horizontal supporting shoe slidably mounted on said steady rest for supporting said workpiece;

a vertical supporting shoe adjustably mounted on the other end of said steady rest for supporting said workpiece;

first feed means mounted between said projection ually operated knob. l

and said vertical supporting shoe for pivoting said steady rest to feed said vertical supporting shoe toward said workpiece;

second feed means mounted on said steady rest for feeding said horizontal supporting shoe toward said workpiece;

drive means mounted on said steady rest for simultaneously driving said first and said second feed means;

a measuring head slidably mounted on said steady rest;

means mounted on said steady rest for moving said measuring head toward and away from said workpiece; and

a single measuring feeler mounted on said measuring head and adapted to engage said workpiece at a point diametrically opposite said vertical supporting shoe for measuring the outer diameter of said workpiece when said measuring head is moved toward said workpiece.

2. The apparatus according to claim 1 wherein said drive means comprises a piston cylinder assembly mounted on said steady rest, a rack operated by said piston cylinder assembly, a first pinion rotatably mounted on said steady rest to be driven by said rack for operating a first feed screw mechanism of said first feed means, and a second pinion rotatably mounted to be driven by said rack for operating a second feed screw mechanism of said second feed means.

3. The apparatus according to claim 2 wherein said second feed screw mechanism comprises a sleeve having said second pinion on the periphery thereof, a feed shaft coaxially extending through said sleeve, said feed shaft threadedly engaging with said horizontal supporting shoe at one end thereof, a manually operated knob fixed to the other end of said feed shaft for adjusting said horizontal supporting shoe and clutch means interposed between said sleeve and said feed shaft for disengaging said feed shaft from said second pinion when said horizontal supporting shoe is adjusted by said manl l i i 

2. The apparatus according to claim 1 wherein said drive means comprises a piston cylinder assembly mounted on said steady rest, a rack operated by said piston cylinder assembly, a first pinion rotatably mounted on said steady rest to be driven by said rack for operating a first feed screw mechanism of said first feed means, and a second pinion rotatably mounted to be driven by said rack for operating a second feed screw mechanism of said second feed means.
 3. The apparatus according to claim 2 wherein said second feed screw mechanism comprises a sleeve having said second pinion on the periphery thereof, a feed shaft coaxially extending through said sleeve, said feed shaft threadedly engaging with said horizontal supporting shoe at one end thereof, a manually operated knob fixed to the other end of said feed shaft for adjusting said horizontal supporting shoe and clutch means interposed between said sleeve and said feed shaft for disengaging said feed shaft from said second pinion when said horizontal supporting shoe is adjusted by said manually operated knob. 